1. Field of the Invention
The invention relates to a planing machine, more particularly to a wood planing machine.
2. Description of the Related Art
Referring to FIGS. 1, 2 and 3, a conventional wood planing machine 10 is shown to comprise a bed 18 over which a wooden work piece (not shown) passes, and an upper housing 11 above the bed 18. A cutting roller 12 is mounted on the upper housing 11 and is rotatable about a horizontal axis. Front and rear feed rollers 13, 14 are mounted on front and rear portions of the upper housing 11 and are rotatable about axes parallel to the cutting roller 12. A motor 15 is mounted on the upper housing 11 and is coupled to one end of the cutting roller 12 so as to drive rotatably the same. The other end of the cutting roller 12 is coupled to the feed rollers 13, 14 such that the feed rollers 13, 14 rotate synchronously with the cutting roller 12.
The upper housing 11 has opposite end portions provided with a pair of upright screw sockets 111, 112. The machine 10 further includes a pair of upright threaded rods 16, 17, each of which has a lower end portion mounted rotatably on the bed 18, and an upper end portion that extends threadedly and respectively through the sockets 111, 112. Each of the threaded rods 16, 17 further has a bevel gear 161 mounted on the lower end portion thereof. A horizontal coupling rod 19 is mounted rotatably in the bed 18, and has opposite end portions provided with a respective bevel gear 191 for meshing with the bevel gear 161 on the adjacent one of the threaded rods 16,17. An adjusting handle 162 is mounted on the upper end portion of the threaded rod 16 so that, upon operation of the handle 162, rotation of the threaded rod 16 is transmitted to the other threaded rod 17 via the coupling rod 19. The machine 10 further includes four pillars 114 that extend upwardly from the bed 18 and slidably through corresponding bores 113 formed in the opposite end portions of the upper housing 11. As such, the upper housing 11 can be raised or lowered relative to the bed 18 when the threaded rods 16, 17 rotate due to operation of the handle 162, thereby adjusting the height of the cutting roller 12 in accordance with the desired thickness of the finished product.
The drawbacks of the aforementioned wood planing machine 10 are as follows:
(I) When the planing machine 10 is in use, the upper housing 11 is constantly subjected to upward forces due to contact between the feed rollers 13, 14 and the work piece. This can lead to undesired movement of the upper housing 11 during cutting, and in uneven thickness at the front and rear parts of the work piece. PA1 (II) Rotation of the threaded rods 16, 17 when raising or lowering the upper housing 11 results in a considerable amount of noise. PA1 (III) The structure of the upper housing 11 is complicated, and results in a high manufacturing cost. PA1 (IV) Because the upper housing 11 has to accommodate the motor 15 for driving the cutting roller 12, the housing 11 is bulky and occupies a large amount of space above the bed 18. This results in inconvenience when replacing the cutting roller 12.